The present invention relates to a socket for electrical parts for detachably holding an electrical part such as semiconductor device (called as "IC package" hereinlater).
In a known art, as "socket for electrical parts" in this kind, there is provided an IC socket for detachably holding an IC package as "electrical part" such as disclosed in Japanese Utility Model Publication No. HEI 6-44050.
One known example of an IC socket of this kind is shown in FIGS. 35A and 35B. The shown IC socket is provided with a contact pin 1 to which a pair of clamping pieces 1a are formed. The clamping pieces 1a are each formed with a contact portion 1b contacting to or separating from a connection pin P of an IC package, not shown, and also formed with a press portion 1c which is pressed by a cam portion 3a of a movable plate 3.
The cam portion 3a is inserted into a space between a pair of press portions 1c, and as shown in FIG. 35A, when the movable plate 3 is depressed, the paired press portions 1c are depressed and widened. Under this state, the connection pin P is inserted into the contact portions 1b through an insertion hole 4a formed to a cover 4.
Next, as shown in FIG. 35B, when the movable plate 3 is raised upward, the cam portion 3a is moved upward, and the connection pin P is clamped by and between the paired contact portions 1b thereby to establish an electrical connection therebetween.
According to the structure mentioned above, the IC package can be mounted or dismounted, without giving no specific insertion or withdrawal force, only by moving upward or downward the movable plate 3, thus improving a working efficiency.
However, in such structure of the conventional IC socket, a pair of contact portions 1b are depressed and widened by inserting the cam portion 3a between a pair of press portions 1c of each of the contact pins 1, and accordingly, it is necessary to insert the cam portion 3a into the paired press portions 1c at the time of arranging the contact pin 1 and the movable plate 3, which results in an adverse workability at an assembling time, and it is also disadvantageous to arrange the contact pins 1 with narrow pitch.
Furthermore, in the prior art mentioned above, the connection pin P of the IC package is held between the contact portions 1b of the paired clamping pieces 1a to achieve an electrical connection. However, because this clamping structure does not attain a wiping effect, it is difficult to realize a stable electrical contacting condition.
In the known art, there is also provided an IC socket of the kind mentioned above such as disclosed in Japanese Patent Publication No. HEI 3-66787 showing an IC package as "electrical part", in which a number of IC leads are formed so as to project downward from a lower surface of the IC package, and these IC leads are arranged in grid shape having vertical (Y-axis direction) and horizontal (X-axis direction) rows.
An IC socket, as "socket for electrical parts", achieving the electrical connection by holding such IC package has an outer rectangular peripheral portion formed of an insulation material and has a substrate on which a cover member is applied to be horizontally movable.
This cover member is formed with a number of IC lead insertion holes having an arrangement corresponding to the grid shaped IC lead arrangement so that the arrangement of the IC lead insertion holes provides a parallelogram shape, and the vertical rows (Y) and horizontal rows (X) of the IC leads are inclined at angles of 45.degree. with respect to the respective side lines of the rectangular outer shape of the cover member. Furthermore, the substrate of the IC socket is formed with a number of contact members having an arrangement corresponding to the arrangements of the IC leads and the IC lead insertion holes.
In such structure, when the cover member is moved in one diagonal direction of the IC lead grid arrangement, the IC package mounted to the cover member is also moved and, hence, the IC leads are separated from or contacted to the contact members.
However, in such conventional structure, in order to ensure displacement or shift amount of the contact member with respect to the IC lead, the arrangement of the IC lead insertion holes is inclined at angles of 45.degree. with respect to the rectangular outer shape of the cover member. Accordingly, the cover member, and hence, an entire structure of the IC socket device has been made large, thus being disadvantageous and providing a problem.